I enjoyed reading through this whole thread, so I thought I'd chime in with my personal experience b/t the original and new PX's.
I bought the PX100-ii because I was able to get $20 bucks off using Amazon points. I have the original PX100 as well, so I was really looking forward to comparing them. I haven't put much time on the PX100-ii yet (maybe 30 hours), but currently, I still prefer my old PX100. I found the PX100-ii with stock pads to be really mid-bass heavy (sometimes muddy) and something was missing (detail) in the upper mid-range compared to the PX100. I also noticed that the pads were thicker, so I switched them out with the Radio Shack replacement pads for the KSC-75/35. The center of these pads are thinner, while the edges still have good thickness. It didn't altogether cure both of my issues, but did help out. The mid-bass is not nearly as overpowering anymore and the upper mid-range doesn't seem to be masked as much. I prefer the new beefier headband and single cable the PX100-ii offers, but still can't bring myself to like the sound more than my 6-7 year old PX100. They just seem more detailed and balanced, which I personally prefer. BTW, my PX100 has the KSC75/35 replacement pads on it as well. I'm hoping the PX100-ii will open up some with more time, but even if it doesn't, I do enjoy it as is............just not first on my list. For anyone finding both PX100 and PX100-ii to be too bassy even with EQ off, I would recommend using the bass reducer on iPod/iPhone/iPad. I keep my EQ off. Good Luck!